Main reactions of the pathway:
The center reactions of the pathway can be summarized as follows:
![1318_Main Reactions of Pentose Phosphate.png](https://www.expertsmind.com/CMSImages/1318_Main%20Reactions%20of%20Pentose%20Phosphate.png)
The pathway has three stages:
Stage 1 - Oxidative reactions which convert glucose 6-phosphate into ribulose 5-phosphate generating two NADPH molecules
Glucose 6-phosphate is oxidized through glucose 6-phosphate dehydrogenase to 6-phosphoglucono-δ-lactone (producing NADPH) and this is then hydrolyzed through lactonase to 6-phosphogluconate. 6-phosphogluconate is then converted through 6-phosphogluconate dehydrogenase to ribulose 5-phosphate. This is an oxidative decarboxylation for instance the 6-phosphogluconate is oxidized and a carbon is removed as CO2. These reactions are shown as follows:
![1365_Main Reactions of Pentose Phosphate1.png](https://www.expertsmind.com/CMSImages/1365_Main%20Reactions%20of%20Pentose%20Phosphate1.png)
Stage 2 - Isomerization of ribulose 5-phosphate to ribose 5-phosphate
the ribulose 5-phosphate is now converted to ribose 5-phosphate through isomerization, a reaction catalyzed through phosphopentose isomerase:
![369_Main Reactions of Pentose Phosphate2.png](https://www.expertsmind.com/CMSImages/369_Main%20Reactions%20of%20Pentose%20Phosphate2.png)
Stage 3 - Linkage of the pentose phosphate pathway to glycolysis via transke- tolase and transaldolase
If at any time only a little ribose 5-phosphate is needed for nucleic acid synthesis and other synthetic reactions it will tend to build up and is then converted to fructose 6-phosphate and glyceraldehyde 3-phosphate through the enzymes transketolase and transaldolase. These two products are midway of glycolysis. Thus, these reactions provide a link among the pentose phosphate pathway and glycolysis. The outline reactions are shown follows.
![1433_Main Reactions of Pentose Phosphate3.png](https://www.expertsmind.com/CMSImages/1433_Main%20Reactions%20of%20Pentose%20Phosphate3.png)
Details of these reactions, displaying the structures of the molecules included, are given in Figure. These reactions need xylulose 5-phosphate as well as ribose-5- phosphate. The Xylulose 5-phosphate is an epimer of ribulose 5- phosphate and is establish through phosphopentose epimerase:
![1368_Main Reactions of Pentose Phosphate4.png](https://www.expertsmind.com/CMSImages/1368_Main%20Reactions%20of%20Pentose%20Phosphate4.png)
Whole the reactions in this stage can be summarized as:
![2235_Main Reactions of Pentose Phosphate.png](https://www.expertsmind.com/../CMSImages/2235_Main Reactions of Pentose Phosphate.png)